1. Field of the Invention
The present invention relates to an electronic circuit device, and particularly to an electronic circuit device including a circuit board on which electronic parts are mounted.
2. Description of the Related Art
As this type of electronic circuit device has been hitherto proposed an electronic device equipped with a circuit board having electronic parts mounted therein and plural lands formed on the surface thereof so that bumps or conductive balls are joined to the plural lands, a flexible wiring board having wiring conductors which are patterned in a resin film having flexibility and an electric insulating property so as to extend in a direction separating from the circuit board, and lands for the wiring conductors which are connected to the bumps or conductive balls of the circuit board, and mold resin for sealing an electrical connection portion between the flexible wiring board and the circuit board through the electronic parts, the circuit board and the bumps or the conductive balls (for example, see JP-A-2006-140273 (Patent Document 1)).
In a case where the lands at the circuit board side are connected to the lands at the flexible wiring board side through the burns or the like as in the case of the technique described in the Patent Document 1, a wire boding step which causes increase of the cost can be omitted to thereby reduce the cost, and also a space required for the electrical connection between the circuit board and the flexible wiring board. However, in a case where the lands at the circuit board side are connected to the lands at the flexible wiring board as in the case of the technique described in the patent document 1, when vibration acts on the circuit board or the like, the stress around the lands of the flexible wiring board is increased, so that the flexible wiring board may be damaged or reliability of terminal connection may be lost. Furthermore, when thermal impact is applied to the circuit board or the like, the stress around the lands of the flexible wiring board is increased due to the difference in thermal expansion coefficient between the circuit board and the flexible wiring board, so that the flexible wiring board may be damaged or the terminal connection reliability may be lost.